This invention relates to intermediates for the preparation of cephalosporin antibiotics. In particular, it relates to 7-amino-3-pyridiniummethyl-3-cephem-4-carboxylic acid hydrothiocyanate salt and 7-amino-3-(substituted-pyridiniummethyl)-3-cephem-4-carboxylic acid hydrothiocyanate salts and to a process for preparing the hydrothiocyanate salts.
The semi-synthetic cephalosporin antibiotics are often prepared by the N-acylation of the appropriate 7-amino-3-cephem nucleus compound. Among the semi-synthetic cephalosporins that can be prepared in this manner are the 7-acylamino-3-quaternary ammoniummethyl-3-cephem-4-carboxylate antibiotics, e.g., cephaloridine and ceftazidime. The 3'-pyridinium nuclei useful in the synthesis are, therefore, valuable intermediates for such antibiotics. The availability of these nuclei in stable, non-hygroscopic form is highly desirable and could allow for bulk storage of the nucleus intermediate for later use in preparing the desired antibiotic.